ViewSonic VA702-3 Service Manual page 18

14.318 MHz crystal is recommended.
b) Analog to Digital Converter:
The MST8111A chip has three ADC's (analog-to-digital converters), one for each color (red, green and blue) .The analog
RGB signals are connected to MST8111A as described below
Pin Name
Red +
Red -
Green +
Green -
Blue +
Blue -
c) OSD : The MST8111A has a fully programmable ,high-quality OSD controller. The on-chip static RAM(4096 words by 24 bits)
stores the cell map and the cell definitions.
d) MTV312 Micro controller: The MTV312 micro controller(MCU) serves as the system micro controller. It' s programs the
MST8111A and manages other devices in the system such as the keypad, the backlight, LED, audio and non-volatile RAM.
using general purpose input/output (GPIO) pins.
Pin number
21
13
14
25
9
24
16
37
34
23
42
41
32
3
36
e) Panel Power Sequencing ( VDDCTRL1, 2) ( Pin 32, 3) : The MTV312 has two dedicated outputs VDDCTRL1 and 2
( Pin32 and Pin3) to control LCD power sequencing once data and control signals are stable.
f) Panel interface (Pin 1~25, Pin75~128) : The MTV312 driver interface is highly programmable. It supports dual bus / dual port
for SXGA drivers.
6.1.2 Power Regulator MC34063A (U6),AIC1739 (Q4) : The MC34063A is a monolithic control IC containing the primary functions
required for DC to DC converters. The device consists of an internal temperature compensated reference, comparator, controlled
duty cycle.
ViewSonic Corporation
Pin Number
63
62
60
59
58
57
Pin Name Pin Number Usage
P1.3 Key / Power on ,off
P3.4 NV_RAM (U4) SDA
P3.5 NV_RAM (U4) SCL
P1.7 Key_down
P6.3 Key_right
P1.6 Key_up
P6.2 Key_left
P4.1 Key_mute
P5.6 VGA connector
P1.5 Key_select
P5.3 LED_red
P5.4 LED_green
P6.6 LCD panel power1 on / off control
P5.0 LCD panel power2 on / off control
P4.0 Backlight on / off control
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VA702-3_VA702b-3